A paving machine can be used in the laying of bituminous roadway mat. The typical paving machine employs a screed assembly (sometimes referred to as a floating screed) for spreading and compressing a bituminous material to form a smooth surfaced roadway mat. The screed assembly typically has a set of screed extensions, slidingly attached to a main body of the screed assembly (herein referred to as a main screed), that allow an operator to control and % or select a width of the screed assembly. These screed extensions are typically connected to a linear power source (e.g., a bi-directional hydraulic cylinder or other similar activator), which is selectively operable in response to controls disposed at an operator control station. This permits the operator to control the position of the screed extensions in response to changing requirements as the paving machine progresses. For example, this permits the operator to accommodate obstacles in the path of the paving machine (e.g., sewer drains, manhole covers, and/or the like) and also permits overwidth paving of the road surface to accommodate roadway features (e.g., driveway entrances, tie-ins, and/or the like). The screed assembly can be a rear mount screed assembly (i.e., a screed assembly in which the screed extensions are mounted behind the main screed relative to the direction of travel of the paving machine) or a front mount screed assembly (i.e., a screed assembly in which the screed extensions are mounted in front of the main screed relative to the direction of travel of the paving machine).
The paving machine typically includes a storage means for receiving and containing a discreet quantity of loose bituminous aggregate material, and a material flow means for conveying the bituminous aggregate material to the roadbed. The loose material is then displaced laterally in front of the screed assembly. As the paving machine progresses along the roadbed, the screed assembly engages the loose material, plowing under and compressing the material into the desired roadway mat. Typically, endgates are provided on outer, distal ends of the screed extensions in order to ensure that the material disposed in front of the screed extensions is not shunted aside, beyond the width of the screed assembly. In some cases, means for providing the lateral disposition of the material is a flighted auger providing two oppositely directed flights from a centerline of the paving machine (e.g., in order to provide disposition of an equal amount of material toward each outer edge of the screed assembly). However, the arrangement of the main screed and the screed extensions can introduce material segregation and/or material flow issues that can negatively impact a quality of the roadway mat leveled by the screed assembly.
One attempt to address one such issue, “streaking” in the roadway mat, is disclosed in U.S. Pat. No. 6,106,192 that issued to Blaw-Knox Construction Equipment Corp. on Aug. 22, 2000 (“the '192 patent”). Per the '192 patent, streaking occurs when a section of the roadway mat appears brighter in appearance or “shinier” than other portions of the roadway mat, and occurs in sections of the roadway mat that are leveled by a region of a front mount screed assembly at transitions from inner ends of the screed extensions to outer ends of a main screed. The '192 patent postulates that streaking occurs due to fine particles of the material tending to accumulate at the inner ends of the screed extensions (such that the streaked sections are formed with a higher concentration of fine-grained material), and/or due to the outer sections of the roadway mat being leveled by the screed extensions prior to an inner section being leveled by the main screed. The '192 patent discloses a flow modifying device, for use in a front mount screed assembly, that includes a deflector member connected with a screed extension and having a flow surface facing toward a central axis of a main screed. Per the '192 patent, the flow surface is contactable with paving material and is configured to displace the material toward the central axis when the paving machine moves in the intended travel direction.
While the flow modifying device of the '192 patent is aimed to address streaking caused by use of a front mount screed, the flow modifying device does not address material segregation and/or material flow issues seen with the use of a rear mount screed assembly. For example, in a rear mount screed, the main screed has a sharp (e.g., 90 degree, square, perpendicular, and/or the like) corner and end face at ends of the main screed. In operation, as material flows around and/or near these sharp corners of the main screed, the material may be pinched between an end face of the main screed and an endgate of the screed extension. Such pinching can result in increased wear on a component of the rear mount screed assembly (e.g., the end face of the main screed, the endgate, and/or the like) and/or material segregation at or near the corner of the main screed. Further, when the screed extension is retracted from an extended position (e.g., due to a change in a desired width of the roadway mat), the retraction of the rear mount screed assembly can be impeded when, for example, the material is compressed between the end face and the endgate such that the screed extension binds, stalls, and/or is otherwise rendered unable to retract to a desired position.
The main screed with angled end faces of the present disclosure can be used in a rear mount screed assembly in order to solve one or more of the problems set forth above and/or other problems in the art.